Bobbin-case for sewing machines



' 23, 1940. J. D. KARLE BOBBIN CASE FOR SEWING MACHINES Filed March 22, 1939 n mu 1 I n flrvucnto c (John, D. [far-la Patented Apr. 23, 1940 UNITED STATES PATENT OFFICE BOBBIN-CASE FOR SEWING MACHINES Application March 22, 1939, Serial No. 263,318

8 Claims.

This invention relates to lock-stitch sewing machine bobbin-cases, more particularly of the type disclosed in U. S. Patent No. 2,154,403; Apr. 11, 1939, and characterized by being made in two sections, one of which, the base-section, is journaled in a rotary needle-loop-taking hook and the other of which, the cap-section, is releasably connected to the base-section and carries the bobbin-thread tension-device. The two sections, when assembled, encase the bobbin or spool on which the lower thread is wound.

The present invention has for an object to increase the bobbin-thread capacity of a threadcase, such as shown in my said copending application, without increase in the diameter of the thread-case bearing rib or increase in the overall axial thickness of the bobbin-case.

In the present instance, advantageous features described and claimed in said U. S. Patent No. 2,154,403 are retained and a further increase in bobbin size is attained, without increase in overall dimensions of the bobbin-case, by modification of the latch-mechanism which releasably connects the cap and base-sections of the bobbincase together.

In the bobbin-case of said U. S. Patent No. 2,154,403, the circular head 01' the cap-section was made thick enough to support the conventional double-deck latch which has been commonly used commercially for many years. I have, in the present instance, discarded this conventional latching device which requires a relatively thick cap-section head to accommodate it, and have substituted therefor a latch device which is quite independent of the thickness of the head of the cap-section on which it is mounted. According to the present improvement the head of the capsection is made comparatively thin and the latch is let into a radial slot or cut-away in said head; the latch handle or finger-piece being little or no thicker than the head of the cap-section. The latch is also preferably provided with an eccentrio portion which, when the latch is opened,-

bin-case; the cap-section and bobbin having been removed. Fig. 3 is a diametrical section of the complete bobbin-case, the latch being closed. Fig. 4 is a similar sectional view with the latch open. Fig. 5 is a sectional view, similar to Fig. 4, 5 of the cap-section and bobbin removed from the base-section. Fig. 6 is a side elevation of the thread-case showing the latch keeper spring. Fig. 7 is a side elevation of the cap-section showing the bobbin-thread clearance groove leading away from the free end of the bobbin-thread tension-spring. Fig. 8 is a similar view completely showing the bobbin-thread tension-spring. Fig. 9 is a perspective view of the cap-section with the latch removed. Fig. 10 is a perspective view of the latch element alone, and Fig. 11 is a perspective view of the bobbin-thread tensionspring.

The bobbin-case comprises abase-section A and a removable cap-section B. The base-sec- 10 tion A is cup-shaped and is formed externally at its rim with the usual peripheral bearing rib l by which it is journaled in the internal bearing groove of a conventional rotary hook member, such as disclosed in the U. S. patent to Kessler, in No. 2,085,699, of June 29, 1937. The base-section A is also formed with the axial arbor or post 2 which, at its free end, is undercut at 3 to provide the overhanging lip 4. The base-section A is otherwise constructed substantially in accordance with the disclosures of said Kessler patent and said U. S. Patent No. 2,154,403 and has the usual rotation-restraining notch 5, loop-controlling flange B and stationary hook 1 common to thread-cases of the prior art. The base-section A is also counterbored internally at 8 to receive the skirt portion 9 of the cap-section B, which counterbore does not extend beyond the peripheral bearing rib I and hence does not weaken the support for such bearing rib.

The cap-section Bis formed with a thin circular head ill from the center of which extends the tubular arbor I l adapted to fit over the basesection arbor 2 and receive the bobbin or spool l2 for free turning movement thereupon. The tubular arbor of the cap-section B is internally provided at its base, close to the plane of the inner face of the circular head 8 with a diametrically disposed pivot pin i 3 for the latch-lever II the finger piece or arm I 5 of which is received in the radial slot or cut-out l6, Fig. 9, in the circular head l0 when the latch is closed. The arm l5 of the latch-lever l4 has a depending tongue I! formed with a lateral ridge l8 which snaps under the free end I! of the keeper spring 2| secured by screws 2| to the base-section A, as shown in Fig. 6. The latch-lever I4 is formed in that portion thereof within the tubular arbor II with a tongue 22 which, when the latch is closed, Fig. 3 enters the notch 3 under the lip 4 of the arbor 2 and locks the cap-section A to the base-section B. Back of the tongue 22 the latchlever I4 is formed with a bobbin gripping surface portion 23 which is eccentric to the pivot l3 and, when the latch is opened, Figs. 4 and v5, binds against the inner surface of the tubular portion l2 of the bobbin and thus grips the bobbin for removal of the latter with the cap-section A.

Mounted as usual on the outer surface of the skirt portion 9 of the cap-section A is the curved bobbin-thread tension-spring 24, Fig. 8, having at its free end the inturned lip 25 notched at 26 to receive and guide the bobbin-thread 21, Fig. 1, which leads tangentially away from the bobbincase in the groove 28.

By the means described I have been able to v materially increase the axial length 01' the bobbin l2 without increase in the axial thickness of the bobbin-case, resulting in a gain oi. 33% in bobbin-thread capacity over the capacity of the conventional bobbin of the Kessler Patent No. 2,085,699, or a gain of 10.8% over the capacity of the bobbin disclosed in said U. S. Patent No. 2,154,403.

It will be seen in Fig. 1 that the latch-lever I5 is inclined downwardly at an acute angle to the horizontal. This inclination of the latch-lever renders the finger piece or arm l5 thereof readily accessible to the operator for manipulation.

The invention is not to be understood as limited to the details of construction of the preferred embodiment of the invention shown and described as it is obviously susceptible of material modification within the scope of the invention.

Having thus set forth the nature of the invention what I claim herein isi 1. In a. sewing machine bobbin-case, a basesection having an axial post formed with a notch, a cap-section having a circular head and an axial tubular arbor received on said post, and a latchlever pivoted on said cap-section within said tubular arbor and having a portion engaging the notch in said post when the latch is closed.

2. In a sewing machine bobbin-case, a basesection having an axial post formed with a notch, a. cap-section having a circular head and an axial tubular arbor received on said post, and a latch-lever pivoted on said cap-section within said tubular arbor and having a portion engaging the notch in said post when the latch-is closed, said latch having a surface portion eccentric to its pivot and arranged to bear outwardly against the inner surface of the bobbin-tube when the 'latch is opened.

3. In a sewing machine bobbin-case, a cupshaped base-section having a peripheral bearing rib and an axial post, a cap-section having a circular head and an axial tubular arbor received on said post, said head having a radial cut-out therein and said post being notched at its free end, and a latch-lever fulcrumed in said tubular arbor and having a tongue received in said notch, said latch-lever having a finger piece received in amanro said cut-out, and means to yieldingly retain said latch-lever in closed position. 4

4. In a sewing machine bobbin-case, a cupshaped base-section having a peripheral bearing rib and an axial post, a cap-section having a circular head and an axial tubular arbor received on said post, said head having a radial cut-out therein and said post being notched at its free end, a latch-lever iulcrumed in said tubular arbor and having a tongue received in said notch, said latch-lever having a finger piece received in said cut-out, and means to yieldingly retain said latch-lever in closed position, said means including a keeper spring screwed to the outer wall of said base-section.

5. A sewing machine bobbin-case having detachably connected base and cap-sections, the base-section having a center post with an undercut adjacent its free end, said cap-section having a circular head and an axial tubular arbor, a pivot pin passing substantially diametrically through said tubular arbor close to the plane of the inner face of said circular head, a latch-lever carried by said pivot pin and formed in that portion thereof within said tubular arbor with a locking tongue entering said undercut and with a bobbin gripping portion eccentric to said pivot 6. A sewing machine bobbin-case having detachably connected base and cap-sections, the base-section having a center post with an undercut adjacent its free end, said cap-section having a. circular head and an axial tubular arbor, a pivot, pin passing substantially diametrically through said tubular arbor close to the plane of the inner face of said circular head, a latchlever carried by saidpivot pin and formed in that portion thereof within said tubular arbor with a locking tongue entering said undercut and with a bobbin gripping portion eccentric to said pivot pin, said latch-lever'also including a finger piece having near its free end a keeper extension, and a keeper spring mounted on said base-section in position to yieldingly engage said keeper extension when the latch-lever is closed.

7. A sewing machine bobbin-case comprising a cup-shaped base-section having a peripheral supporting bearing and a notched center post, a cap-section having a circular head and a central tubular arbor received upon said center post, said cap-section also having a peripheral skirt portion, a thread-tension spring applied to the outer surface of said skirt portion, and a. latchlever fulcrumed at a fixed point on said capsection and having a portion extending into said tubular arbor and into the notch in said center post.

8. A sewing machine bobbin-case comprising, a cup-shaped base-section having a center post, a cap-section having a circular head and'a tubular central arbor normal to the plane of said head and received on said center post, and a latch carried by said cap-section and releasably engaging said post, said latch being substantially contained within the space between the planes of the outer and inner faces of said head and the cylinder defined by the outer surface of said tubular arbor.

JOHN D. KARLE. 

